People on here shouldnt give up so easily, I have a solution for failed to boot brick.
Download moto-fastboot, and unzip to C:\moto-fastboot
DL here:
http://www.android-advice.com/file-downloads.php?filename=Atrix_Root_Files
Download system image for 2.3.4 and unzip to moto-fastboot folder
DL here
http://www.android-advice.com/file-downloads.php?filename=Atrix_Gingerbread_4591_ROM
Download atrix oem unlock and unzip to moto-fastboot folder
DL here:
http://gititbit.ch/pub/unlock.zip
open cmd and navigate to C:\moto-fastboot\
Force fastboot on phone by holding down PWR and VOL UP while inserting battery.
Type these commands:
moto-fastboot oem unlock (it will show atrix ID re-enter with ID at end of line)
when finished, then enter these commands:
moto-fastboot flash boot boot.img
moto-fastboot flash system system.img
moto-fastboot -w
moto-fastboot reboot
When it reboots, you will be back to stock, fully restored!!
I then used Pete's Motorola Tools to root my atrix.
Info and DL here
http://www.psouza4.com/Bionic/
yes it did work on my atrix make sure usb debugging is on and unknown sources checked.
I then installed CWM to my Atrix
DL here
http://forum.xda-developers.com/showthread.php?t=1475444
unzip to moto-fastboot, put atrix in fastboot mode and open cmd, navigate to moto-fastboot folder and type this:
moto-fastboot flash recovery recovery.img
Reboot and you are DONE!!!! All thats left is to find a ROM and you are good to go.